Technical Field
The present invention relates to a support mechanism for supporting various articles or any other kind of load, and particularly to a load support mechanism for supporting a target article at a desired position in such a way as to able to move the article.
Description of the Related Art
Conventionally, various support mechanisms are proposed to support an article, such as a computer, a television monitor device, a top table of an OA desk or work table, or a heavy object, at a desired height position in such a way as to be able to move the article up and down. For example, what is known is a monitor device support mechanism that can move the monitor device up and down and position the monitor device with a constant support force (Such a mechanism is disclosed in Jpn. Pat. Appln. Laid-Open Publication No. 2002-215055 and Jpn. Pat. Appln. Laid-Open Publication No. 2002-303304, for example).
The monitor device support mechanism disclosed in Jpn. Pat. Appln. Laid-Open Publication No. 2002-215055 includes at least one cam; at least one cam follower member; an energy storage member, such as a spring; a moving body, on which a monitor device is mounted; and an arm member, which connects the cam follower member to the moving body and which can freely swing. In the monitor device support mechanism, as the moving body moves along a fixed base, the spring is compressed or stretched by the cam. The spring force of the spring is transformed by a surface of the cam into a reaction force against the cam follower member. A first reaction force component that is part of the reaction force and is applied in a movement direction of the moving body generates a support force for the moving body and the monitor device, via the arm member.
According to Jpn. Pat. Appln. Laid-Open Publication No. 2002-215055, the shape of the cam is designed in such a way to keep a constant level of the first reaction force component in the movement direction. The combination of such a spring and the shape of the cam keeps an almost constant level of the force that presses the moving body, which is moving, and the monitor in the movement direction. Therefore, when a slight force is manually applied to the moving body or the monitor device, the monitor device can be easily moved. When the force is released, the moving body and the monitor device stop at a new support position thereof. What is also disclosed in Jpn. Pat. Appln. Laid-Open Publication No. 2002-215055 is an adjustment mechanism that adjusts a variable load on the monitor device support mechanism by rotating cams around shafts and thereby adjusting the distance between the cams.
What is disclosed in Jpn. Pat. Appln. Laid-Open Publication No. 2002-303304 is another force adjustment mechanism that adjusts an almost constant level of a support force similarly applied to a moving body and a monitor device. The force adjustment mechanism is designed to support various weights of load in a monitor device support mechanism by changing the effective length and pre-tension of a plate spring that presses a cam follower (roller) against a guide surface of a cam.
In order to support a load, such as a conduit, with a roughly constant level of spring biasing force, a suspension device is known (Refer to U.S. Pat. No. 4,613,119, for example): the suspension device includes a main spring mechanism, which supports a load in a suspended manner, and an additional spring mechanism, which compensates for a change in the biasing force of the main spring mechanism. The main spring mechanism includes an up-down-direction main spring, which is mounted between an upper head member that is fitted onto a vertical sleeve and fixed to an upper end of the sleeve and a lower spring bearing that is fixed to a casing. By the upward biasing force of the main spring, a downward load that acts on a lower end of the sleeve is supported.
In the additional spring mechanism, a pair of cam followers, which are provided on the head member, a pair of cam arms, which are attached to the casing in such a way as to freely swing, a pair of cam surfaces, which are formed integrally with the cam arms, and a pair of additional springs, which horizontally press the cam arms to press the cam surfaces against the cam followers, are disposed symmetrically in the left-right direction. The cam follower roll along the curved cam surface in such a way as to offset an up-down-direction movement of the sleeve caused by the load as a change in the biasing force of the main spring caused by the up-down-direction movement is offset by the biasing force of the additional spring.